System of electric signaling.



'L'. COHEN.

SYSTEM OF ELECTRIC SiGNALING.

APPLICATION FILED JUNE 30, I916.

Patented Dec. 31, 1918.

.l iieutenant Colonel George t). Squier. U.

'it is produced.

vides at each station. a secondarv receiving UNIT D. STATES LOUIS COHEN,OF WASHINGTON, DISTRICT OF GEORGE O. SQUIER, OF WASHINGT SYSTEM OFELECTRIC SIGNALING.

Application filed June 30, 1915. 5

To all uflioiu it may concern:

Be it known that I, LOUIS Cones, ac'itizen of the lfnited States,residing at Washington. in the 'Districtof Columbia, have iiivented acertain new aiid'uselul System of Electric Signaling, of'whieh thefollowing is a speciti 'ation,

This invention relates to animprovement in the art of signaling byelectricity, particularly through means ofelectrical energy distributedby wires. It is designed primai'ilv as an improvement- .in' the artoi.duplex telegraphy. and is particularly. adapted to cable telcg'raphy.

It is well known that in any system of tinplex telegraphv heretoforeused, a' socalledartificial line is necessary. Such systems are veryexpensive in the equipment required. particularly"when employed in longdistance submarine work.

The present invention dispenses with the artificial line or cable .iiiduplex systems of frequencies. so that each current becomes cha'acteristie oil the sendingstation at which The invention alsoprocircuit. which is so related to the local sending equipment and to,the line that it is at fected only by current from a distant station andnot by the Stlltllllg current of the local station. This result isaccomplished by so arranging the circuits that the local sending currentwill be self-neutralizing in the recciving circuit. while the latterislelt subfeet to manifestations-ot energy froni'the distant station.More specifi will stated, these results are accomplished by having thelocal receiving: circuitinductively related to the line and also to thecircul't of-the, localv sending equipment. but the inductive relation tothe latteeis of such character that Specification of Letters Patent.

COLUMBIA, ASSIGNOR 013 on, DISTRICT OF COLUMBI PATENT OFFICE.

ONE-HALF TO Patented Dec. 31, 1918. i-ial No. 106,906.

two currents are induced in the local receiving circuit w liicli re ofopposite phase and, therefore, seek to neutralize each other. To insurethe elnninatioii of any possible residual effects of the to incompletebalance in circuit, the latter loop circuit which nance with thefrequency of the local send int, current, and,

local transmitter, due the local receiving is made to include also a istuned to be in resotherefore, acts in the nature of a very highresistance with respect to the local transmitting current without anyefl'cct upon the CUIIGDLfIOIH the distant station other tha resistanceof the n that of the actual ohmic loop circuit.

Several methods of putting the invention into etl'ect are hereinsuggested by way'of illustration. element through For instance, thetransformer which the receiving circuit is related to the line, may bedivided or put into the form 0 are in series with the line with thelocal transmitter.

f two transformers which and in multiple so thatthe current from thelatter divides itself and flows in opposite directions through them,thus setting up the atoresaid' opposed currents in the receiving circting equipment may nit. Or the local transmitpendent local circuit whichis inductively related to the line cuit. coupled through and the localreceiving cira transformer with this local transmitting circuit, andthrough an independent .transtornier with the line;

the arrangement being sucli that the currents induced in the receivingcircuit through its respective transformers.

therefore. tend t( this arrangement viouslv describet the frequeiic ofrent ma) be em cuit to eliminate are opposed and, neutralize each other.In

. as in the arrangement prel. a loop circuit tuned to the localtransmitting curbe arranged in an inde-.

)lo ved' in the receiving cirresidual etl'ects, and a loop circuitis.pret'erabl v also employed in the local transmitting frequencycircuit and is tuned to the of the distant ti'ans'lllittillg current. inorder to exclude from the local sending circuit. distant its influencewho ceiving circuit.

cuit when arran energv. received from the station and cause the latterto exert ll v or mainl upon the re- The local t 'ansiiiittiiig eirgedindependently and in inductive relation to the line, may be (611- V,

i the. receiving circuit or inpletl directly witl d ircctly the-rewit anintermediate 11. through the nieditrin of transformer circuit; the

last named feature facilitating adjustment of phase relations betweencurrents induced in the receivingcircllil by the local tran mit directindependent local sendingcircuit. in

cluding the windings of two transformers by which it is coupled.respectively. with the main line and the recen'mg circuit. while thereceiving circuit has an indepeiulent' transforniencminection with themain line:

i and Fig. 3 showing' a modification of the system shown in Fig. :2. inwhich the receivmgmrcuit still remains directlycoupledwith the groundedwinding of the main circuit. but.

is coupled with the transmitting: circuit through the medium of anintermediate transformer circuit that facilitates adjustment of phaserelations between the locall vinduced currents in the receiving!circuit.

Referring to the drawings. a line or cable 1 is equipped at itsrespective ends with up? paratus arranged according to the presentinvention. for simultaneously sending and receiving messages. Thisequipment consists, according to the illustrative embodr ment of Fig. 1,in the primary windings 2, 2*, introduced between the cable 1 and groundconnection 7 and forming parts of a divided transformer or twotransformers whosesecondary windings 3, 3 are included in the receivingcircuit containing any suitable type of'receiving instrument orindicating device 10. 4 represents an adjustable resistance or any otherdevice suitable for inductance.

varying the aniplitude'of or otherwise affect- 111g the sending current,for signalinq. 5 is avariable condenser and 5 a variable 6 is a sourceof alternating current, and 7 a ground connection. These sending andreceiving equi nnents are duplicated at theopposite end, wherecorresponding parts bear similar, reference characters, distlnguished'by the prune mark.- The altern'ating current sources (3. (3, however,will be adapted to generate different frequencies, so that the output ofeach is characteristic of its-ownstation.

If new currentis transmitted from the alternating current source 6, forinstance, such current. divides at the point 21 and flows partly throughthcprimary-Q .to the cable 1, and partly throughthc. primary 2. to

ground at-T. Now suppose We adjust the numberof'turns .in' thepr1nmr1es'2 and 2 s' sc thatrthe impedance of 2 is larger than 5 5ancggorwistance in the priniary 2 so that Inductance 5 and condenser 5that 0:52, and also establish a ratio of reactloop circuit arcsoadjusted that the relation of the current from source U flowing into thecable 1 and only a small part shunted through branch 2 to the ground atT". 'e

shall further have the currents in the two branches in phase andconsequently the induced currents in the secondaries 3. ll, opposite inphase. By properly adjusting the coupling of the two prinn'iries 2. 2.with their respectivesecondaries 3. 3*. which is likewise a conditionreadily attainable, we. shall have no current in the reccivin circuit 3;3.- 10. In otherwords. the ctlect of the. current from source (1 .willbe neutral ized or balanced inthis receiving circuit and the latter willbe left withoutany nuinifestation of etfect from the transmitting:equipment. and. therefore. free to'be inliuencerl .by incoming signalsfrom the equipment at the distant end of the cable.

In order to insure absolutely against any manifestation of influence ofthe sending current, in the local receiving circuit. the latter isprofided. with a-further safeguard in' the form of a loop circuit 8. 9LIt'now the inductance 8 and the capacity 9 of the expressed bythefornn-lla r:-'.\' l,(=:l. when N is the frequency of the currentgenerated 1 alternator (3. I the inductance 8. and (f the a pacitytl.then the loop circuit has the, same effect as that of an enormousresistance introduced into the circuit, which may be of the order()f'l00,000 ohms or so. and as a consequence any small residual current,which would fiowin the receiving secondary circuit 3, 3, 8,.9, 10, iscompletely eliminated from said circuit. and the delicate receivinginstrument "1-0 will be in, no wise affected by :thesending eq'uipmentfBut with the arrangement as just described, current from the distantsource 6, having a characteristic frequency different from that ofthealternator 6, flows through both primaries 2. 2

in the same direction; thc cnrrent induced in the secondaries 3; i -ofthe receiving circuit reinforce eachother instead of being opposed, andthe effect is readily translatable into an intelligible manifestation inthe re-' ceivingr instrument '10. Furthermore, the loop-circuit 8. 9, inthe reccivingcircuit, having been adjusted for resonance with thefrequency of the source (3, is out of tune for the frequency -of thecurrent received from the source (3'', even though the frequenciesbetween these stations differ as little as 10% t0 15%;' hence, the loopcircuit will offer no greater resistance to the sum of the currentsinduced in the windings 3, 3* by the distant source, than the actualohmic resistance of thednductance coil- 8.

can readily 188 he adjusted so that, in combination. with the inductanceof coil 2 and cable 1, the nummum impedance is; offered for current fromthe source 6, and at the same time, the impedance offered to the currentfrequency of I the distant source 6 and condenser 5, with that of the ofthe received current flowing through WindingQ will pass on to thewinding 2 with very little shunted through the "local generatingequipment, and thusinsure the desirable conditions, already described,in the receiving circuit; I

All the conditions described with refer once to t-hestation ofalternatingsource 6 by the inductance 5 I apply literally to the stationof alterna tor From the foregoing, will be c lear that "the current fromone station has no effect upon the receiving circuit at that station;

'ceived over on the contrary each. receivingcircuit, with its'delicateinstrument for'rendering in telligible the signals received, remains atall times subjectalone to. the incoming signals; hence, messages canbetransmitted and resame timef A modified system for use in practisingthe to which the alternating sources 6, 6 at the respectivestations,.-.whieh generate currents 1 station, While those coupled withprimaries other station. At the the frequencies of the connectionsdirectly 11 and 14' are located at 15 and 16 at the same time;.thereceiving circuits have independent transformerwith the line.represented by windings l7, 18 at one station, and 1'3, l8 at theotherstation. The receiving secondary. circuits in this installation includethe loop circuits 8. 9, S, 9. and re- (relying instruments 10. 10', asin Fig. 1. In this arrangement. the loop circuits 8. 9 and 8, 9areadjustcd to be in rcsonancemfor currents generated by sources 6 and6, respectively. Also the transformers 14,16 and 17. 18 at a station areso adjusted thatjthe current from source .6 induces equal and oppositecurrents in the receivingcircuit at that station. Now. since the loopcircuit- 8, 9 1s.,adjusted for resonance to the frequency of the currentfrom source 6,. no perceptible current from the source 6 can flow in thelocal At the same time, current fromthe distant end of the line will notafiect the sending circuit of source 6, be-

will be, large as compared;- winding :2. so that mostsendingxan'dreceiving circuits throughthe the same. cable at one and thephase'relations of the the receiving circuit. by the local sending artof duplex telegraphing as hereindescribed, is illustrated in Fig. 2,according.

only the currents from the .cause the loop circuit 1:2. 13 is tuned tothe frequency of current from saiddistant end (source (3).'and,consequently, ollcrs considerable resistance to flow of current of thatfrequency; hencc..current from the distant. station passes on throughthe winding 17 to ground at 7. and therebyinduces current in the winding15 ot' the receiving c'ircuit, unopposed by any current through.transfmmer ll. l6, and thus atl'ects the receiving device 10 inaccordance with signals from the distant stat-ion alonc. The sameconditions prcvail at the station of the opposite end of the cablewhcreidcntlcal instrumentalities are employed and indicated by similarreference characters distinguished by the prime mark. .-Fig. 3 shows aninstallation similar to Figs 2, witlrthe modification that a thirdlocal' circuit is coupled through transformer 14, 1.6 with thetransmitting circuit. and

or receiver 10. "The advantage'of thus cstablishing induction relationbetween the medium of a third circuit. lies in the facility therebyafforded of exactly ad usting the currents induced in circuit. so thatsaid currents will neut 'al-ize each other.

The general principles of the system of circuits des *ribed. above.particularly ifcm bodied as suggested in Fig. 2' or Fig. may be readily:extended to include multiplex- -ingthat is sending and receivingseveral messages at the-same time over the same line. For the case ofquadrnplexing. for

instance, it is only necessary to have two transmitting and tworeceiving circuits at each end. and the frequencies. of the currentsgcneratedhy the alternator-s .to be different from each other: also thecircuits in regardto transformenaction and loop circuits will have tobase adjusted as to exclude fronr'each receiving circuit. not localtransmit tors, but also the current from one ofthe transmitters at theother end. That is, make each receiving circuit electrically opaque tocurrentspf three different frcqucncics'. by multiplying the describedsystcm of neutralizing transformers and by 'llllI'OtllHlXW three loopcircuits in series. each one adjusted tobc in resonance with thefrcqueir. cics. of one of thc currents to be excluded. and admit onlythe current of one definite frequency, namely that desired to afl'ccttl1e receiver.

1. A system of duplex electric signaling. without artificial line, saidsystem compris- 1 mg a line, an independent receiving circuitinductively related to theline, and a sending equipment, including asource of alternatingcurrent. delivering its current to the transmittingcircuitand arranged to induce urrents of same magnitude but oppositephase in -the local receu mg circuit. so that ceiviug circuit being sorelated, inductively,

to the line as to receive maximum effect I of the distant transmittinge'quipn'ient but arranged to receive from the local source,

two currents of same magnitude but opposite phase, so that. said localreceiving circuit is not affected by the local transmitter.

3. A system of duplex electric signaling comprising a .line, tworeceiving circuits at the respective ends of the line. two transmittingequi ni'ients at the respective ends .of the line. including sources ofalternating current of. different frequencies; each receiving circuitbeing so related. inductively, to the line as to have induced therein.two currentsof opposite phase from the local transmitter. and. twocurrents of same phase from the distant transmitter, whereby each localreceiving circuit .devehiips no manifestation from the local.transmitting equipment. but maximum manifestations from the current fromthe distant transmitting equipment.

4-. In a system of duplex electric signaling, a line. an independentreceiving cir cuit inductively related to the line, and a sendingequipment including a source of alternating current delivering itscurrent to the transmitting circuit but inducing two currents of equalmagnitude but opposite phase in, anth therefore. not affecting thereceiving circuit, and said receiving circuit including a loop circuitadjusted to be in resonance with the frequency of the alternatingcurrent in the local sending equip ment. 1 v

5. A system of duplex electric signaling comprising a line. tworeceiving circuits at the respective ends of the line, two'transmittingequipments at the respective ends of the line including sources ofalternating current of different frequencies; each I receiving circuitbeing so related, inductively.

to the line-as to receive from the local source, two currents of samemagnitude but opposite phase, and, therefore, not to be afiected by thelocal transmit-ting equipment, but. to receive maximum effect of thedistant transmitting equipment; and; each receiving circuit including aloop circuit adjusted to be in resonance with the frequency of thealternating current in the local sending equipment.

5. Ina system of alternating current duplex electric signaling, a. line,an independent receiving circuit inductively related to the line. and asending equipment including a source of alternating current, deliveringits current to the transmitting circuit but delivering two currents ofsame magnitude but opposite phase to, and, therefore, not affecting thereceiving circuit; said transmitt'ingequipment being in a localindependent circuit, which also includes a loop circuit tuned to be in.resonance withthe frequency of current from the distant station.

7: A system of duplex'electric signaling so current of difierentfrequencies; each receivequipment, but to tuned to be in resonance withthe frequenc of the current of the distant transmitting equipment. j i.V

8. A system of duplex electric signaling comprising a line. tworeceiving circuits at the respective ends of the line, two transmittingequipments at the respective ends of the line, including sources ofalternating curreutof different frequencies; each receiving circuitbeing: so related, inductively, to the line as to receive from the localsource, two currents of same magnitude but opposite phase,and,'therefore, not to be affected by the local transmitting; equipment,but to receive maximum effect of the distant transmitting equipment;each of said transmitting equipments being in an independent localcircuit inductively related to the line; each of said local receivingcircuits having transformer conneetion with the local trans- 'mittingcircuit, and its inductive relation to the line con'iprising anindependenttransformer-connection; the current vin each local receivingcircuit, induced through its two said transformerconnections, by thelocal transmitting circuit, being of oppo phase, and each localreceiving circuit; also ,includinga loop circuit adjusted in resonancewitlrthe frequency of the local transmitting current. v j

9. system of duplex electric signaling comprising a line, two receivingcircuitsat the respective ends of the line, two transmitting equipmentsat the respective ends of the line, including sources of alternatingcurrent of different frequencies; each reconnections,

ceivi-ng circuit being so related, inductively, to the line as toreceive from the local, source, two currents of same magnitude butopposite phase, and, therefore, not to be affected by the localtransmitting equipment, but to receive maximum effect of the distanttransmitting equipment; each of said transmittingequipments being in anindependent local circuit inductively re lated to the line; each 'ofsaid local receivmg circuits having transformebconnection with the localtransmitting circuit, and its inductive relation to the line comprisingan independent I transformerconnection; the current in eachlocalreceiving circuit, induced through its two said transformerby thelocal. transmitting .cir-

' cuit, being of Opposite phase; and e'achlocal transmitting circuitincluding a loop circuit of the tuned to resonance with the frequency ofcurrent of difi'erent requencies; each receiving circuit being sorelated, inductively, to

the line as' to receive from the local source, two currents of samemagnitude but opposite phase, and, therefore, not to be affected by' thelocal transmitting equipment, but to receive maximum effect of thedista'ut trans:

mltting cquipmcntyfeach of said transmit-- ting equipments being in anindependent 10- cach 0t; said local receiving circuits havingtransformer-connectio'nwith the local transmitt-ing circuit, and itsinductive relation to the line comprising an independenttransformer-connection; the currcntiu each local receiving circuit,induced through its two said transformer-conncctions, by the localtransmitting c ircuit, -"bcing of opposite phase; and each-localreceiving circuit also including a loop circuit adjusted in resonancewith the frequency of the local trans mitting current; and each localtransmitting circuit including a loop circuit tuned to resonance withthe frequencyof the distant transmitting current; i i

The foregoing specification signed at Washington, District of Columbia,this 29;

day of June, 1916.

. LOUIS .co mN.

4 35 .cal circuit inductively related to the line;

